:checked

版本：CSS3

CSS 伪类:checked选择器表示任何处于选中状态的radio(<input type="radio">), checkbox(<input type="checkbox">)或(<select>)元素中的option HTML元素("option")。

语法:

E:checked{sRules}

匹配用户界面上处于选中状态的元素E。(用于<input>为radio与checkbox时)

/* 匹配任意被勾选/选中的radio(单选按钮),checkbox(复选框),或者option(select中的一项) */
:checked { 
  margin-left: 25px; 
  border: 1px solid blue; 
}

用户通过勾选/选中元素或取消勾选/取消选中，来改变该元素的:checked状态。

Note:因为浏览器经常将<option>视为可替换元素，因此不同的浏览器通过:checked伪类渲染出来的效果也不尽相同.

浏览器支持


IE9+以及新版浏览器都支持

例子

//html

<div>
  <input type="radio" name="my-input" id="yes">
  <label for="yes">yes</label>

  <input type="radio" name="my-input" id="no">
  <label for="no">no</label>
</div>

<div>
  <input type="checkbox" name="my-checkbox" id="opt-in">
  <label for="opt-in">check me!</label>
</div>

<select name="my-select" id="fruit">
  <option value="opt1">apples</option>
  <option value="opt2">grapes</option>
  <option value="opt3">pears</option>
</select>

//CSS

div,
select {
  margin: 8px;
}

/* labels for checked inputs */
input:checked + label {
  color: red;
}

/* radio element, when checked */
input[type="radio"]:checked {
  box-shadow: 0 0 0 3px orange;
}

/* checkbox element, when checked */
input[type="checkbox"]:checked {
  box-shadow: 0 0 0 3px hotpink;
}

/* option elements, when selected */
option:checked {
  box-shadow: 0 0 0 3px lime;
  color: red;
}

yesno

check me!

这个例子利用了:checked伪类，让用户基于复选框的状态切换内容，而无需使用JavaScript。

//html

<input type="checkbox" id="expand-toggle" />

<table>
  <thead>
    <tr><th>column #1</th><th>column #2</th><th>column #3</th></tr>
  </thead>
  <tbody>
    <tr class="expandable"><td>[more text]</td><td>[more text]</td><td>[more text]</td></tr>
    <tr><td>[cell text]</td><td>[cell text]</td><td>[cell text]</td></tr>
    <tr><td>[cell text]</td><td>[cell text]</td><td>[cell text]</td></tr>
    <tr class="expandable"><td>[more text]</td><td>[more text]</td><td>[more text]</td></tr>
    <tr class="expandable"><td>[more text]</td><td>[more text]</td><td>[more text]</td></tr>
  </tbody>
</table>

<label for="expand-toggle" id="expand-btn">toggle hidden rows</label>

//CSS

/* hide the toggle checkbox */
#expand-toggle {
  display: none;
}

/* hide expandable content by default */
.expandable {
  visibility: collapse;
  background: #ddd;
}

/* style the button */
#expand-btn {
  display: inline-block;
  margin-top: 12px;
  padding: 5px 11px;
  background-color: #ff7;
  border: 1px solid;
  border-radius: 3px;
}

/* show hidden content when the checkbox is checked */
#expand-toggle:checked ~ * .expandable {
  visibility: visible;
}

/* style the button when the checkbox is checked */
#expand-toggle:checked ~ #expand-btn {
  background-color: #ccc;
}

当<label for="expand-toggle" id="expand-btn">toggle hidden rows</label>被点击时，其关联的<input type="checkbox"id="expand-toggle"/>被激活，并且处于选中checked状态。

column #1	column #2	column #3
[more text]	[more text]	[more text]
[cell text]	[cell text]	[cell text]
[cell text]	[cell text]	[cell text]
[more text]	[more text]	[more text]
[more text]	[more text]	[more text]

toggle hidden rows

<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title></title>
<style>
input:checked{
opacity:0.3;
}
</style>
</head>
<body>


<p>给选中的输入元素设置透明度</p>
<input type="radio" checked="checked" value="male" name="gender" />male<br>
<input type="radio" value="female" name="gender" />female<br>
</body>
</html>

给选中的输入元素设置透明度

male
female